The present invention relates to a method of using ultrasonic waves in wound treatment. In particular, the present invention relates to a method of spraying a wound surface using ultrasonic waves for delivering drugs, killing bacteria, cleansing a surface, increasing blood flow and stimulating healthy tissue cells.
Ultrasonic waves have been widely used in medical applications, including both diagnostics and therapy, as well as in many industrial applications. One diagnostic use of ultrasound waves includes using ultrasonic waves to detect underlying structures in an object or human tissue. In this method, an ultrasonic transducer is placed in contact with the tissue (or object) via a coupling medium, and high frequency (1-10 MHz) ultrasonic waves are directed into the tissue. Upon contact with underlying structures, the waves are reflected back to a receiver adjacent the transducer. By comparison of the signals of an ultrasonic wave as sent with the reflected ultrasonic wave as received, an image of the underlying structure can be produced. This technique is particularly useful for identifying boundaries between components of tissue and can be used to detect irregular masses, tumors, and the like.
Two therapeutic medical uses of ultrasonic waves include aerosol mist production and contact physiotherapy. Aerosol mist production makes use of a nebulizer or inhaler to produce an aerosol mist for creating a humid environment and delivering drug to the lung.
Ultrasonic nebulizers operate by passing ultrasonic waves of sufficient intensity through a liquid, the waves being directed at an air-liquid interface of the liquid from a point underneath or within the liquid. Liquid particles are ejected from the surface of the liquid into the surrounding air following the disintegration of capillary waves produced by the ultrasound. This technique can produce a very fine dense fog or mist. Aerosol mists produced by ultrasound are preferred because a smaller particle size of the aerosol can be obtained with the ultrasonic waves. One of the major shortcomings of inhalers and nebulizers is that there are no directed aerosol to the target without an air stream, which decreases the efficiency of ultrasound.
Contact physiotherapy applies ultrasonic waves directly to tissue in an attempt to produce a physical change in the tissue. In conventional ultrasound physiotherapy, an ultrasonic transducer contacts the tissue via a coupling medium. Ultrasonic waves produced by the transducer travel through the coupling medium and into the tissue. The coupling medium is typically a bath of liquid, a jelly applied to the surface to be treated, or a water-filled balloon. Conventional techniques provide ultrasonic waves having an intensity of from about 0.25 w/cm2 to 3 w/cm2 at a frequency of from about 0.8 to 3 Megahertz. The treatment is applied to a skin surface for from about 1 to 30 minutes, two or three times a week. The coupling medium can provide a cooling effect which dissipates some of the heat energy produced by the ultrasonic transducer. More importantly, a coupling medium or direct contact between the tissue and the ultrasonic transducer is necessary to transmit the ultrasonic waves from the transducer to the skin surface because ambient air is a relatively poor medium for the propagation of ultrasonic waves.
Several beneficial effects have been reported from contact ultrasound physiotherapy. For example, the following effects have been associated with contact ultrasound physiotherapy: local improvement of the blood circulation, heating of the tissue, accelerated enzyme activity, muscle relaxation, pain reduction, and enhancement of natural healing processes. Despite these beneficial effects, current techniques of medical physiotherapy using ultrasonic waves are limited by the necessity of providing a direct contact interface between the ultrasonic transducer and the tissue to maintain an effective transmission of the ultrasonic waves from the transducer to the tissue. The necessity of direct contact with or without a coupling medium makes current methods undesirable. Some tissue conditions may be accessible to contact ultrasound devices but would be impractical for contact ultrasound treatment. For example, fresh or open wounds resulting from trauma, burns, surgical interventions are not suitable for direct contact ultrasound treatment because of the structural of the structural nature of the open wound and the painful condition associated with those wounds. Moreover, conventional contact ultrasound may have a destructive effect on these types of open wounds due to the close proximity of an oscillating tip of an ultrasonic transducer relative to the already damaged tissue surface.
It is an object of the invention to provide a method and device for treating wounds.
It is also an object of this invention to provide a method and device for treating wounds using ultrasonic waves.
It is another object of the invention to provide a method and device for delivering drugs and irrigation to wounds.
It is a yet another object of the invention to provide a method and device for the mechanical cleansing and debridement of wounds.
It is a further object of the invention to provide a method and device for increasing blood flow in a wound area.
It is a yet further object of the invention to treat a wound by spraying the surface of the wound with an aerosol mist produced by ultrasonic waves.
These and other objects of the invention will become more apparent from the discussion below.
The present invention concerns a method and device for spraying a wound surface to deliver drugs, kill bacteria, or cleanse a surface by non-contact application of ultrasonic waves. The ultrasonic waves are applied to the wound without requiring direct or indirect (via a traditional coupling medium) contact between an ultrasonic wave transducer and the wound to be sprayed.
Ultrasonic sprayers (Sonic and Materials Inc., Misonix Inc., Sono-Tek Inc.; U.S. Pat. Nos. 4,153,201, 4,655,393, and 5,516,043) typically operate by passing liquid through the central orifice of the tip of an ultrasound instrument. Known applications are essentially industrial, such as a burner or device for coating of surfaces. No ultrasound wound or biological tissue treatment application with such a device has been indicated, with the exception of ultrasound liposuction.
According to the present invention a directed spray of liquid particles produced by contact of the liquid with a free end surface of an ultrasonic transducer is directed onto a wound. The ultrasonic waves cause the spray to project outwardly from the distal end surface, and the particles of the spray provide a medium for propagation of the ultrasonic waves emanating from the distal end surface.
In the method of the present invention, particle spray created by low frequency ultrasound waves and directed at the surface of a wound, can deliver drugs, kill bacteria on the wound, increase blood flow, and/or remove dirt and other contaminants from that surface (mechanical cleansing). This method of drug delivery is particularly advantageous on tissues for which local topical application of a drug is desirable yet contact with the tissue is to be avoided. Furthermore, the low frequency ultrasound waves used in the method energize the drug and cause penetration of the drug below the surface of the tissue. Finally, the bacteria killing method is effective when applied to the surface whether the liquid sprayed is a drug (an antiseptic or antibiotic), oil, saline, distilled water, or the like.
In a device according to the invention, a spray is produced by first delivering liquid to the free distal end surface of an ultrasound tip through the axial (center) orifice or hose. After liquid is delivered to the free distal end surface, ultrasonic waves create the spray, which is directed to a particular targeted surface such a wound. Simultaneously ultrasonic waves are delivered to the wound surface through the spray.
The device must have a nozzle made from a rigid material such as steel (non-disposable) or plastic (disposable). The nozzle allows liquid to be delivered to a lateral surface of the transducer tip or directly to the distal side (radiation surface) of the ultrasound instrument to be sprayed.